package com.ln.avro;

import org.apache.avro.Schema;
import org.apache.avro.file.DataFileReader;
import org.apache.avro.file.DataFileWriter;
import org.apache.avro.generic.GenericData;
import org.apache.avro.generic.GenericDatumReader;
import org.apache.avro.generic.GenericDatumWriter;
import org.apache.avro.generic.GenericRecord;
import org.apache.avro.io.DatumReader;
import org.apache.avro.io.DatumWriter;
import org.apache.avro.specific.SpecificDatumReader;
import org.apache.avro.specific.SpecificDatumWriter;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;

public class NoCodeGenerationDemo {

    public static void main(String[] args) throws IOException {
        // First, we use a Parser to read our schema definition and create a Schema object.
        InputStream resourceAsStream = Thread.currentThread().getContextClassLoader().getResourceAsStream("user.avsc");
        Schema schema = new Schema.Parser().parse(resourceAsStream);

        // Using this schema, let's create some users.
        GenericRecord user1 = new GenericData.Record(schema);
        user1.put("name", "Alyssa");
        user1.put("favorite_number", 256);
        // Leave favorite color null

        GenericRecord user2 = new GenericData.Record(schema);
        user2.put("name", "Ben");
        user2.put("favorite_number", 7);
        user2.put("favorite_color", "red");

        // Serialize user1 and user2 to disk
        File file = new File("users.avro");
        DatumWriter<GenericRecord> datumWriter = new GenericDatumWriter<GenericRecord>(schema);
        DataFileWriter<GenericRecord> dataFileWriter = new DataFileWriter<GenericRecord>(datumWriter);
        dataFileWriter.create(schema, file);
        dataFileWriter.append(user1);
        dataFileWriter.append(user2);
        dataFileWriter.close();

        // Deserialize users from disk
        DatumReader<GenericRecord> datumReader = new GenericDatumReader<GenericRecord>(schema);
        DataFileReader<GenericRecord> dataFileReader = new DataFileReader<GenericRecord>(file, datumReader);
        GenericRecord user = null;
        while (dataFileReader.hasNext()) {
            // Reuse user object by passing it to next(). This saves us from
            // allocating and garbage collecting many objects for files with
            // many items.
            user = dataFileReader.next(user);
            System.out.println(user);
        }


    }

}
